At present, various tissue preservation solutions have been developed and used in transplantation therapy. For development of tissue preservation solutions, components and composition of a new tissue preservation solution are determined, a tissue (organ) isolated from an animal such as rat and the like is immersed in the preservation solution, and the preserved tissue is transplanted to the animal or biochemically evaluated to determine the preservative effect. Therefore, evaluation of the preservative effect of one preservation solution takes an extremely long time, which makes it difficult to rapidly develop a new tissue preservation solution. Accordingly, there is a demand for the development of a method for evaluating a preservative effect of a tissue preservation solution more rapidly and more conveniently.
In the meantime, recent progress in the imaging strategy that explicitly shows real-time biological events in a cell and a molecule has enabled easy understanding of biological process expressed in living animals. The development of molecular tag such as green fluorescent protein (GFP) derived from jellyfish (Aequorea victoria), luciferase derived from firefly (Photinus pyralis) and the like has promoted revolution in the past 10 years, and enabled association of complicated biochemical processes with action of protein in live cells (non-patent documents 1, 2). In particular, imaging using luminescence light offers an important opportunity to study various biological processes in live cells (non-patent documents 2, 3). Bioluminescence light reporters show considerably high signal to noise ratios in mammal tissues, based on which light signals released in normal animals can be quantified by noninvasive measurement methods. The present inventors have heretofore developed GFP transgenic rat, LacZ transgenic rat and luciferase transgenic rat, and reported that graft rejection can be easily observed using tissues derived from these rats (non-patent documents 4, 5).
Non-patent document 6 discloses that GFP emits strong fluorescence even after the death of the cells derived from GFP transgenic rat.    non-patent document 1: Science, vol. 300(5616), p. 87, 2003    non-patent document 2: Nat. Med., vol. 4(2), p. 245, 1998    non-patent document 3: Annu. Rev. Biomed. Eng., vol. 4, p. 235, 2002    non-patent document 4: Biochem. Biophys. Res. Commun., vol. 329(1), p. 288, 2005    non-patent document 5: Transplantation, vol. 81, No. 8, p. 1179-1184, 2006    non-patent document 6: J. Biomed. Opt., vol. 10(4), p. 41204, 2005